In fluid catalytic cracking units, the reaction normally involves intimate contact of a finely divided particulate catalyst with a feed stock. The catalyst is subsequently separated from the converted feed stock. The process occurs at high temperatures and as a consequence, some combustion occurs which creates carbonaceous coatings such as coke. This normally accumulates on the catalyst. The catalyst is typically delivered to a regeneration chamber where a controlled volume of air is introduced to burn the coke. This burning must occur at a temperature sufficiently high to convert the coke into carbon monoxide or carbon dioxide. The temperature must be suppressed sufficiently to prevent the regeneration operation from exceeding temperatures at which the catalyst is damaged. High temperatures will deactivate the catalyst. Normally the regeneration process includes the step of separating flue gases in the regeneration chamber from the finely divided particulate catalyst. This is customarily accomplished in cyclone separators, sometimes in a single stage and other times in a series of separators. Often cyclone separators will be installed in parallel. They return the catalyst to a place of accumulation where it is recirculated back to the reactor. The separators have two outlets, the second devoted to flue gas disposal.
Regenerators are normally quite large and typically require several cyclone separators. The flue gas volume is quite substantial and a flue gas disposal pipe or stack is required. This comprises a substantial portion of apparatus normally placed in a regenerator. The regenerator operates at substantially elevated temperatures, typically in excess of 1,000.degree.F. These elevated temperatures cause expansion of all of the components of the regenerator, including the cyclone separators and associated equipment. Elevation in temperature carries with it the consequential thermal expansion on heating and contraction on cooling.
The present invention provides an improvement for a regenerator. It is particularly directed to the upper portions of the regenerator, and cooperates with the specified number and type of separator means. Avoidance of hot spots in the upper portions of the regenerator may require the operation of six or more cyclone separators located at strategic locations. The present invention ably accomodates any number of separator means and vagaries of placement.